Uniform thickness coatings are often applied over sections of circuit boards. The coatings prevent water vapor, gases, or fluids from corroding the electrical connections on a circuit board. The coatings may comprise a wide variety of materials such as ultraviolet (UV) acrylic gels, moisture and thermal cure silicones, and the like.
The coatings are typically applied to a circuit board using devices such as spray guns or spray nozzles. Such devices generally include a liquid spray material that is atomized by compressed air and is then directed toward the surface to be coated. The spraying devices are commonly attached to an apparatus, such as a multi-degree of freedom robotic positioning apparatus, that provides accurate positional displacement relative to the article being coated.
As electronic components mounted on circuit boards become smaller, and more compactly spaced, previous large diameter spray nozzles can no longer access particular areas of a circuit board. Some tall electronic components protrude a considerable distance from the circuit board. When two or more of these tall electronic components are closely spaced, a large diameter spray nozzle cannot fit between the electronic components. Furthermore, there is now a requirement for providing a small diameter spray pattern with clearly defined edges to provide the accuracy and precision required to produce the spray in the narrowly defined space created by the closely spaced electronic components.